Along with the popularization of smartphones and the like, the use of wideband code division multiple access (WCDMA) 3G and long term evolution (LTE) 4G communication has rapidly increased. General users tend to have a sense of unease about security and privacy. Recently, due to social issues such as communication eavesdropping or monitoring, the sense of unease is getting worse, and demands of users about safe communication are increasing. Accordingly, a secure communication related market has significantly grown in not only the public sector but also the private sector.
However, for existing security related products and services, since a separate server for distributing or managing a key used for encryption is prepared, user information remains in the server, and thus, a risk of an outflow due to a request from a public or private organization still exists, and accordingly, a user still feels unease due to this risk. Therefore, for secure communication, the necessity for using no server, minimizing user information to be recorded in a server if the server is used, or restricting an access right to user information is raised.
In addition, when inter-terminal secure communication is performed, an entire call packet is encrypted and transmitted/received, and thus it is difficult to compatibly use existing communication networks or existing codec algorithms. Accordingly, the necessity for inter-terminal secure communication having an encryption algorithm therein while maintaining compatibility with the existing communication networks or the existing codec algorithms is also raised.